US2862075A

US2862075A - Overcenter spring operating mechanism for an electric circuit breaker

Info

Publication number: US2862075A
Application number: US701591A
Authority: US
Inventors: Philip C Netzel
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1957-12-09
Filing date: 1957-12-09
Publication date: 1958-11-25
Anticipated expiration: 1975-11-25

Description

4 Sheets-Sheet 1 P. C. NETZEL Nov. 25, 1958 Filed Dec. 9, 195'? Inventor: Philip C. Netzel',

bg @His ttorheg.

c. E'rzz-:L 2,862,075

Nov. 25, 1958 p,

OVERCENTER SPRIN ATING MECHANISM FOR AN ELECTRI CIRCUIT BREAKER Filed Deo. 9, 1957 v 4 Sheets-Sheet 2 Inventor:

Nov. 25, 1958 P. c. NETZEL 2,862,075

OVERCENTER SPRING OPERATING MECHANISM FOR AN ELECTRIC CIRCUIT BREAKER Filed Deo. 9, 1957 4 Sheets-Sheet 3 Inventor: Phi ip C. Netzel,

ttorne.

Nov. 25, 1958 P. c. NETZEL OVERCENTER SPRING OPERATING MECHANISM FOR AN ELECTRIC CIRCUIT BREAKER 4 Sheets-Sheet 4 Filed Dec. 9, 1957 In Venter: philip C. etzel be His ttorneg.

United States Patent O GVERCENTER SPRING OPERATING MECHANISM FOR AN ELECTRIC CIRCUIT EREAKER Philip C. Netzel, Swarthmore, Pa., assigner to General Electric Company, a corporation of New York Application December 9, 1957, Serial No. 701,591

5 Claims. (Cl. 20D-70) This invention relates to an overcenter spring operating mechanism for an electric circuit breaker, and it relates more particularly to a circuit breaker operating mechanism wherein an overcenter spring is employed to obtain a snap-action circuit closing operation.

Overcenter spring mechanisms are commonly used for closing and opening low-voltage air circuit breakers having relatively low current ratings. A typical operating mechanism of this type comprises a toggle having one end connected to the movable switch member of the breaker, latching means supporting the other end of the toggle, an overcenter tension spring connected at one end to the knee of the toggle, and means for moving the other end of the overcenter spring in a manner to produce snapaction switch closing movement of the toggle. When a conventional mechanism such as this is applied to circuit breakers having relatively high current ratings, it is necessary to use very strong and heavy overcenter springs, that is, springs having a relatively high spring constant. This is because a large amount of force is required to overcome static friction and inertia of the relatively massive contact structure and related movable linkages of such high current breakers. Since there is a practical limit to the amount of available space in which the operating mechanisms for such breakers can be mounted, the necessary closing force cannot conveniently be obtained by stretching or extending relatively weak springs over a relatively long distance.

The use of relatively heavy and strong overcenter springs in the closing mechanisms of circuit breakers is undesirable for at least two reasons. In the first place, a great deal of force is required while closing the breaker to charge such a spring, that is, to elongate the spring prior to the snap-action closing operation. This is particularly undesirable when the breaker is arranged to be closed manually. Furthermore, both the wear and the possibility of damage to the moving parts of the breaker are increased in proportion to the amount of closing force employed; Accordingly, it is an object of this invention to provide an improved overcenter spring operating mechanism wherein spring force is supplemented by means permitting the use of a weaker overcenter spring than would otherwise be possible.

Another, object of the invention is the provision, in an overcenter spring closing mechanism for an electric circuit breaker, of means arranged to aid the overcenter spring in overcoming static friction and inertia of the movable breaker parts.

Still another object of the invention is to provide an overcenter spring operating mechanism so constructed and arranged that the overcenter spring which is moved to initiate snap-action closing cannot be moved effectively to initiate breaker opening or tripping.

In carrying out my invention in one form, I provide a circuit breaker operating mechanism comprising a toggle connected to close the circuit breaker contacts, an operating member movable between irst and second positions,

2,862,075 Patented Nov. 25, 1958 and an overcenter tension spring coupled to both the toggle and the operating member and effective in response to movement of the operating member from its first to its second position to produce snap-action contact closing movement of the toggle. I also provide rigid means movable with the operating member and engageable with the toggle so arranged as to initiate movement of the toggle while the operating member is being moved between its rst and second positions and before the overcenter spring becomes effective.

In one embodiment of my invention, the rigid means l is arranged to engage the toggle and start contact closing movement thereof as the operating member approaches its second position, whereby it is unnecessary for the overcenter spring to supply sufficient force to overcome static friction and the inertia of the toggle, the contacts and the related movable parts. In a second embodiment of the invention, the rigid means is disposed to engage the toggle at an earlier point in the closing operation, and the toggle is then moved to an intermediate position where it is held by a suitable blocking member. The blocking member is actuated as the operating member approaches its second position to release the toggle and permit snap-action contact closing movement thereof. In the intermediate position of the toggle, the forces resisting closing movement are less and the moment of the force supplied by the overcenter tension spring is increased, whereby a relatively weak overcenter spring may be used to obtain successful breaker closing.

In another aspect of my invention, the toggle, operating member and overcenter spring are so arranged that after the circuit breaker has been closed, movement of the l from the following description taken in conjunction with pivot 14 suitably supported on the base 12. A compresa.

the accompanying drawings in which:

Fig. l is a side elevation of a circuit breaker having an operating mechanism constructed in accordance with one embodiment of my invention, the circuit breaker being shown in its closed circuit position;

Fig. 2 is a section taken along lines 2---2y of Fig. l;

Fig. 3 is an exploded perspective view, partly in section, of the breaker operating mechanism shown in Fig. l;

Fig. 4 is a view similar to that of Fig. l but with the circuit breaker and the operating mechanism being shown in an open circuit position;

Fig. 5 shows the mechanism in its reset position;

Fig. 6 shows the mechanism in a position through which it passes after resetting and shortly before snapaction closing operation takes place.

Fig. 7 is a simplified side elevation of a circuit breaker operating mechanism constructed in accordance with a second embodiment of my invention, the mechanism being shown in a position through which it passes after resetting and at -a relatively early stage in the closing operation; and

Fig. 8 is `a view of the Fig. 7 operating mechanism in its closed circuit position.

Referring now to Fig. l, I have shown a circuit breaker comprising a frame member for mounting a base member indicated generally by the reference numbers 11 and 12, respectively. A relatively stationary contact 13 is mounted for slight pivotal movement on a stationary 3 sion spring biases Contact 13 counterclockwise about its pivot, as is shown in Fig. 1. A cooperatingY movable contact or switch member 16jis mounted for pivotal movement about` a stationary pivot 17 which isl suitably supported on the base 12. A stop 18AV mounted on frame 11 determines the open circuit position of' contact 16 (see Fig. 4), and pivotal movement ofA contact 16( in a clockwise direction carries this contact into circuit making engagement with the stationary Contact 13 thereby completing the circuit represented by

conductors

19 and 20 in Fig. l. .Thec'oinpression spring 15 permits contact 13 to/yield slightly duringthe circuit'closing operation, thereby providing a wiping action between the two cooperating contacts. i

The switch Contact ormember 16 isl moved between its open circuit and closed circuit positions by means of a series of force and motion amplifying members and linkages indicated generally by the reference number 21 in Fig. 1. The interconnected linkages and members 21 comprise, for example, a member 22 pivotally mounted Ion base 12' and connected by` aylink 23 to the switch member 16, and a' pair of identical 3-sided

members

24 and 25 pivotally mounted on frame 11 and connected to the member 22` by a pair of links 26' and 27 As best seen in the perspective view Fig. 3, the pair of links 26 and 27 are interconnected with the pair of

members

24 and 25 by means of a pin 28 laterally extending between members 24'and 25. The'

members

24 and 25 are pivot.- ally supported on' a common rod or shaft 29 fixed to the frame 11.

' The movement of the force and motion amplifying means 21l is controlled by a toggle 3() which is pivotally pinned at 31 to the

members

24 and 25. The toggle 311 comprises one pair of identical links 32 and 33 which are connected to another pair of

identical links

34 and 35 by means of a laterally extending pin 37 best seen in Fig. 3. Pin 37 forms the knee of the toggle. One end of links-32, 33 is connected by means of the pin 31 to the linkages and members 21 and hence to the movable switch' member 16. The' opposite end 38 of the

toggle links

34, 35 is connected to a pin 39 which is carried by a pair of generally C-shapcd guide members 411 and 41. The guides 45.3 41 form part of a latching means which releasably restrains the end 38 of toggle 311 in a latched position. `In the closed circuit position of the switch member 16, as is shown in Figs. 1, 2, 3 and 8, toggle end 38 is held in its latched position and the toggle knee 37 assumes a position determinedby a shoulder 36 of the upper end `of the guides 41), 41. The guides 40, 41 and the links 32, 33'of toggle 30 are respectively disposed in the same planes, and as'isfmost clearly indicated in Fig. 3, upward` movement of the toggle knee 37 is stopped by the links'3'2, 33 engaging the shoulder 36 of guide members 40,'y 41.

Thelatching means for the toggle end 38 includes the pair of guides 40 and 41 and a latch 42 disposed laterally intermediate the guides. As best seen in Fig. l, the guides 40, 41 are pivotallyV supported at ltheir upper end on a rod .43y which is fixed to the circuit breaker frame 11. Spanning the other ends of the C-shaped guides 4t), 41 is a roller 44 which cooperates with the free end of latch 42. The latch 42 is'pivoted at' one end on a rod 45 xed to the frame 11 as shown in Fig. 2. As is clearlyl indicated in Fig. l, a tension spring 46 is provided to bias latch 42 clockwise about pivot 45 into engagement with the roller 44of the guides 40,41. -In the closed cir` cuit and reset positions of the operating mechanism, the roller 44 is releasably restrained in an appropriate notch 47 in latch 42, whereby guides 40, 41 hold the toggle end 38 in its latched position.

t As will become apparent hereinafter, the force exerted by the guides 40, 41 through roller 44 `on the cooperating surface of notch 47 tends to pivot latch 42 counterclockwise on rod 45, buta prop 48 isv provided, as is clearly shown in Fig. 1, to prevent such counterclockwise movement. The prop 48 is fixed at one end to a trip shaft 49. Suitable means are provided to biasV the prop 48 into a latching position wherein the free end ofthe prop engages ya roller 50 mounted on latch 42 to releasably hold the latch and prevent counterclockwise motion thereof.

Guide releasing operation of the latch 42 is initiated by rotating trip shaft 49 in a counterclockwise direction which removes prop 48 from roller 50 and permits counterclockwise movement of latch 42. The counterclockwise rotation of trip shaft 49 can be achieved by any number of well-known means, either electrically or manually. For example, manually moving the paddle 51 shown in Fig. l in the direction of the arrow will accomplish the desired result. When latch 42 moves counterclockwise and releases guides 40, 41 in the manner described above, the guides will pivot about rod 43 in a clockwise direction from the iirst position shown in Fig. 1 to a second position shown in Fig. 4, thereby initiating a circuit opening operation. A

To provide breaker opening and closing force, a pair `of overcenter tension springs 52 and 53 are provided. One end of each of these springs is connected' to the toggle 30 preferably at knee 37. The other ends of

springs

52, 53 are secured by means of a pin 55 to apir of operating

members

56 and 57, best seen in Fig. 3'. i-EachI of the operating

members

56, 57 is mounted for pivotal movement' on the rod 253 which is supported by frame 1'1 The operating members arem'ovable about pivot 29"y be-' tween first and' second' positions at opposite ends of their normal range of movement. The operating

members

56 and 57 are inftheir second position in Figs; 1, 3, 4' and 8 vvhil'e in Fig". 5 they are shown in the rst position. l

For moving" the operating

members

56, 57 between the first and second positions, a handle mechanism, indieated generally by reference number 53 in Fig. l, is'provided. The handle mechanism comprises a shaft 5 9" which' is journaled in a stationary escutcheon plate 6) fixed to frame 11. Ancho-red to the outer end of the shaft 59 is a handle member 61 which is manually operable to elfe-ct limited rotation of the shaft 59. Anchored to the inner end of the shaft 59 is a crank 62 having at its radially outer end an axiallyextending crankpin 63. A tie bar 64 positively couples crankpin 63 to a laterally extending pin 65 which bridges the operating members 56 and'57`, as best seen in Figs. 2 and 3. `It will be under! stood by those skilled in the art that the handle mechanism 58 has been shown merely for the sake of illustratic-n and that other means', such as a solenoid for example, could be coupled to pin 65 in order to move the operating

members

56, 57.

Rotary movement of the handle member 61 carries the operating

members

56, 57 between their first and secondpositions. Such pivotal movement of the operating members will carry pin 55, to which one end `of the overcenter springs 52, 53`is attached, through an arc indicated by reference number 66 inA Figs. l, 6 and 7. It can be observedv in Fig. l that the toggle 36 is' stopped in a position, as determined by shoulder 36 of guidesY 4Q, 41, such that pivotal movement of the operating

members

56, 57 from their second to their iirst positions will not carry pin below the extended centerline of

toggle links

34, 35. in other words, the centerline of

links

34, 35 does not intersect the arc 66. This means that with the circuit breaker in its" closed cir-cuit position, force exerted by the over-center springs 52, 53 will always maintain the toggle 39 in its Vstopped position shown in Fig. l, even if the operating

members

56, 57 were moved to their first position.

In accordance with my invention, suitable holding means are providedto restrain or block the operating

members

56, 57 in` their second position when the circuit breaker is closed. As can be seen in Fig; l, the holding :means comprises, for example, a hook-likecatch 67 havingiarecessed portion 68 and mounted for pivotall movement on a shaft 69 ixed to fra'nie 11. A suitablef spring 70 is provided to bias catch 67 into engagement with a 'stop pin 71 that is also fixed to frame 11. The movable catch 67 cooperates` with the laterally extending pin 55 carried by operating

members

56, 57 to restrain or hold the operating members in their second posltion.

The operating members are released or unblocked -when the circuit breaker is open. Whenever the tripping shaft 49 is rotated to unlatch the toggle and permit circuit opening operation (which operation will be explained in detail hereinafter), the guides 40, 41 move pivotally about rod 43 in a clockwise direction to their second position determined by stop pin 71 which is engaged by an enlarged roller 72 disposed on the pin 39 extending between the guides 4t) and 41. See Figs. 3 and 4. But before engaging the stop pin 71, roller 72 engages a camming surface 73 located on the under side of catch 67 thereby pivoting the catch clockwise against its bias and lifting it clear of the operating member pin 55, as is most clearly shown in Fig. 4. In this manner, the operating members are unblocked or released upon opening of the circuit breaker.

In order to return the guides 40, 41 to their first position when resetting the operating mechanism (which resetting opcration will be described in detail hereinafter) a laterally extending pin 74 is connected between the operating

members

56 and 57. This pin engages the upper surface 75 of guides 40, 41 when the operating members are returned to their first position after an opening operation of the breaker, whereby the guides 40, 41are pivoted counterclockwise about rod 43 and returned to their rst position. See particularly Fig. 5.

In accordance with my invention, each of the operating

members

56 and 57 is provided with an inturned rigid projection or lug overlapping the corresponding end of pin 37 which forms the knee of toggle 30. For reasons to be explained more fully hereinafter, these lugs are arranged slidably to engage knee 37 thereby initiating switch closing movement of toggle 30 during clockwise movement of the operating

members

56, 57 intermediate their irst and second positions. In the embodiment of my invention illustrated in Figs. 1-6, the rigid lugs appended to the operating

members

56 and 57, which lugs have been identified by the reference numbers 76 and 77, respectively, are disposed tolirst engage the toggle knee 37 as the operating members approach their second position, for example at the point that is illustrated in Fig. 6.

From the foregoing detailed description of the structure of the first embodiment of my improved circuit breaker operating mechanism, its mode of operation may now be readily followed. Fig. 1 illustrates the circuit breaker in its closed circuit position. The overcenter springs 52, 53 connected to the knee 37 of toggle 30 transmit force through shoulder` 36 and pin 39 to guides 40, 41. This force establishes in guides 40, 41 a torque in a clockwise direction with respect to rod 43. Clockwise movement of guides 40, 41 from their first position shown in Fig. 1 is prevented by the latch 42 which engages in its notch 47 the guide roller 44.

The circuit breaker isl tripped by rotating tripping shaft 49 in a counterclockwise direction to remove prop 48 from latch roller 50, thereby releasing the latch 42 for counterclockwise movement `on rod 45 in accordance with the force exerted on the forward edge of notch 47 by the guide roller 44. `This action releases the guides 40,141 which are then free to pivot on rod 43 in ac- `cordance with the clockwise torque produced by the overcenter springs 52, 53; As the guides 40, 41 are driven clockwise by the overcenter tension springs 52, 53, pin 39 is carried through an arc which intersects the centerline of the springs. The toggle end 38 must follow pin 39 along `its arc, and as pin 39 moves toward its intersection with thecenterline of the springs, the toggle 30 is moved in a manner `to pull

members

24, 25 of the force and motion amplifying means V21 in a clockwise direction thereby initiating circuit breaking or4 opening movement of the switch member 16. It. will be noted that the initial opening movements of the various movable linkages and members of the operating mechanism are encouraged and aided by the compression spring 15 acting through the relatively stationary contact 13.

When the guide pin 39 passes beyond the centerline of the overcenter tension springs 52, 53, a snap-action switch opening movement of the toggle 30 takes place. The overcenter springs 52, 53 will now pull the toggle knee away from the shoulder 36 of guides 40, 41 and move the toggle links 32, 33 at an accelerated rate to complete the circuit opening operation of the breaker. The open circuit or tripped position of the circuit breaker is shown in Fig. 4, with the switch member 16 resting in its open circuit position on stop 18 and the guides 40, 41 stopped in their second position by roller 72 engaging stop pin 71. It will be observed in Fig. 4 that the roller 44 located at the lower end of the guides 40, 41 is in engagement with a cooperating surface of the free end of latch 42, latch 42 being held against roller 44 by the action of the tension spring 46.

During clockwise pivotal movement of the guides 40, 41, and just prior to the guides reaching their second position as determined by stop pin 71, the guide roller 72 engages the lower surface of catch 67 thereby tilting the catch clockwise on shaft 69. This action lifts the catch from the pin S5 of the operating

members

56, 57, thereby releasing or unblocking the operating members which had been restrained in their second position by catch 67. The circuit breaker operating mechanism is now in condition to be reset.

To reset the circuit breaker operating mechanism, handle member 61 is rotated so as to carry crankpin 63 downward and consequently pivot the operating members 56, 5'7 counterclockwise on rod 29. The counterclockwise movement of the operating members from their second to their first position drives the guides 40, 41, whose upper surfaces '75 are engaged by the operating member pin 74, in a counterclockwise direction about rod 43 toward their first position. As a result, the toggle 30 is moved in a manner that produces very little motion in pin 31, and both ends of the overcenter tension springs 52, S3 are moved approximately the same amount.

During the resetting operation, guide roller 44 slides across the cooperating surface of the free end of latch 42, and when the guides 40, 41 reach their first position the roller 44 has reached the notch 47 in latch 42. This permits the latch 42 to pivot clockwise on rod 45 in accordance with the bias provided by spring 46. The prop 48 is now able to move into its latch holding position, whereby the latch 42 cannot be moved counter-clockwise and the guides 40, 41 are held in their first position releasably to restrain the toggle end 38 in its latched position.

The reset position of the circuit breaker operating mechanism isillustrated in Fig. 5. The circuit breaker s now in condition to be closed.

To close the breaker after a reset operation, the handle member 61 is rotated to raise crankpin 63 thereby pivoting the operating

members

56, 57 clockwise about rod 29. The operating members while moving clockwise from their first to their second positions carry pin 55 along the arc 66. The arc 66 is so disposed with respect to the toggle knee 37 in its reset position that the

overcenter tension spring

52, 53, connected between pin 55 and knee 37, are stretched or charged as the operating

members

56, 57 move clockwise. arc 66 is reached at which the operating member pin 55 passes through the extended centerline of

toggle links

34, 35. As the pin 55 moves beyond point 78, switch closing force is exerted on toggle knee 37 by the overcenter tension springs 52, 53. That is, the moment of A point 78 on the 7 toggle end 3S' is pivotally attached is' now in a direction tending to rotate toggle links 3'4', 35 counterclockwise on pin 39 and to pull the toggle knee 37 upward as viewedv in--Figs 5 and 6. Such upward movement of the toggle knee, Vwith toggle end 38 heldin its latched position, wouldl close the circuit breaker Switch member 16'.

In accordance with my invention, I useovercenter

tension Springs

52, 53 that are too weak to initiate movement of toggle knee 37 as the pin 55 moves beyond point 78 in arc 66. In other words, the static friction and the inertia of the various movable parts of the breaker will resist switch closing movement of toggle with a force that is greater than the opposing force applied to the toggle by the stretched overcenter springs 52', 53. Among the advantages of using weak overcenter springs having relatively low spring constants, as pointed out in the introductory portion of this specication, are that a relatively small amo'untrof force is required to charge or elongate the springs during the closing operation and that the wear and possibility of damage -to the movable parts are reduced. p v

When the operating

members

56, 57 have been moved to a position such as is shown by way of example in Fig. 6, the lugs 76, 77 of these members engage the toggle knee 37. Further clockwisemovement of the operating members will result in lugs 76, 77 carrying toggle knee 37 upward, whereby switch closing movement of the toggle 30-and interconnected linkages and members is initiated. The overcenter springs 52, 53, which have now been stretched about twice as much as they were stretched at the previously mentioned point 78 of the operating member pin 55, are selected so that their force is su'icient to accelerate the already moving parts and produce a snap-action switch closing operation. Thus, by using lugs 76, 77 movable with the operating

members

56, 57 to initiate movement of the toggle 30' as the operating members approach their second position, it is unnecessary for the overcenter tension springs 52, 53 to ,overcome the static friction and inertia of the movable parts, and much weaker overcenter tension springs may be used to eiect snap-action switch closing movement than would otherwise be possible.

The snap-action switch closing movement of toggle 30, once initiated by the lugs 76, 77 slidably engaging toggle knee 37, is obtained by the overcenter tension springs

L

52, 53 pulling

toggle links

34, 35 counterclockwise about pin 39'which is releasably restrained in a latched positionl by the latching means previously described. This movement causes toggle links 32, 33 to carry pin 31 and hence members 24, in a counterclockwise direction with 'respect to rod 29. As a result, the various parts of the force and motion amplifying means 21 are moved in a manner to pivot the switch member 16 clockwise about its pivot point 17 into circuit making engagement with the cooperating stationary contact 13. The closed circuit position of the circuit breaker is shown in Fig. l. It will be noted that the switch closing motion of the toggle is stopped by the shoulder 36 of the guides 40, 41, whereby further collapse of the toggle is prevented.

As the operating

members

56, 57 move into their second position, pin 55 engages the free end of catch 67 thereby tilting catch 67 clockwise on shaft 69. See Fig. 6. In the second position of the operating members, pin 55 has passed beneath the recess 68 in catch 67, thereby permitting the catch to tilt counterclockwise on shaft 69 in accordance with its bias spring 70. Now pin 55' is captured by the catch 67 and the operating members 56, y57 are held or blocked in their second position as can be seen vin Fig. l. The catch 67 is rendered ineffective to hold the operating members only after a circuit breaker tripping operation which results in the guide roller 72 engaging Vthe catch surface 73, as has been fully described hereinbefore. I p

Even if the operating members` 5.6, 57vwere permitted to be returned to their first position while the toggle end 38 is held in its latched position, circuit openingoperation could not result. Thisl is' because the toggle 30 is stopped in a position, as is clearly illustrated in Fig; 1, such that the extended centerline of the toggle links 34; 35 does not intersect the arc 66 of the operating member pin 55. Therefore, the tension springs 52, 53 cannot' be carried over the center of

toggle links

34, 35 by moving the operating members from their second to their first positons, and the moment of the spring force will maintain the toggle in its stopped position. s

The second embodiment of my invention illustrated in Figs. 7 and 8 differs from the embodiment described above in that the inturned rigid projections or lugs appended to the operating

members

56 and 57 are disposed in a different manner than the lugs 76 and 77, and a mov` able blocking member and cooperating actuating means have been added. In all other respects the structure of the circuit breaker operating mechanism shownv in Figs.' 7 and 8 is the same as that describedy hereinbefore, and the same reference numbers are used to identify the corresponding parts.

In Fig. 7 the near-side operating member 56 has been removed in order to simplify the visual representation of the operating mechanism. The operating member 57 is provided with a lug 79 disposed to first engage the toggle knee 37 at a relatively early stage in the closing operation, for example at the point that is illustrated in Fig. 7. It can be observed that the operating member pin 55 to which is attached one end of the overcenter tension springs 52, 53 has not yet passed through point 78 which marks the intersection of the extended centerline of

toggle links

34, 35 with the arc 66.A In other words, the toggle 30 isset in motion by lug 79 slidably engaging knee 37 even before the overcenter springs 52, 53 have passed over the center of

toggle links

34, 35. Y

The foregoing modification of the previously described arrangement permits a more even distribution of the force required to move the handle mechanism 58 during the closing operation. This can be explained by recalling that the ytension in the overcenter springs 52, 53 is proportional to their elongation, and therefore the force required to charge or stretch these springs increases roughly linearly as the operating

members

56, 57 are movedV bfv the handle mechanism from their rst to their second positions. By arranging the lug 79 as is shown in Figs. 7 and 8, the additional force necessary to move the toggle 30 and the various linkages interconnected ,theretoupon lug 79 engaging the toggle knee 37 is applied whilethe force required for charging the overcenter springs is still relatively small. Thus there is a relatively even distribution of the forces required to move the operating

members

56 and 57, and it is unnecessary to apply a greatly lncreased amount of force toward the end of the closing operation. d

As the operating member 57 is moved beyondthe point lllustrated in Fig. 7 during a closing operation, lug 79 carries the toggle knee 37 upwards. l Such upward movement of the toggle Vknee is eventually stopped by a movable blocking member 80 which is disposed to engage the toggle knee and stop the toggle 30 in an intermediate position. The circuit breaker switch member 16 has not reached its closed circuit position with toggle 30 stopped in its intermediate position. The blocking member 8,0 is used to prevent premature closing of the circuit breaker.

vThe blocking member 80 may be pivotally mounted on the rod 29 which is ixed to the circuit breaker frame 11. As is shown in Figs. 7 and 8, suitable bias means" such as a torsion spring 81 is provided to urge member 80 in a clockwise direction on rod 29. Clockwise movement of member 80 is stopped by a pin 8.2 which is aiixed to suitable actuating means comprising for example a lever 83. Lever 83 is pivotally mounted intermediate its ends on rod 43 which is xed to the frame 11. One end of thelever 83 i s provided' with Va generally U-shaped depression 84 which cooperates with pin 29 to dene oppo- 9'` site limits of movement of the lever 83. In other Words, the lever 83 may be pivoted or tilted in a clockwise direction on rod 43 until one inside edge of the U-shaped depression 84 engages the rod 29 as shown in Fig. 8, and counterclockwise tilting of lever 83 on rod 43 is similarly stopped by theopposite inside edge of depression 84 engaging rod 29 as shown in Fig. 7. The other end of the actuating means or lever 83 comprises an elongated portion having a surface 8S which cooperates with the laterally extending pin 74 of the operating

members

56, 57.

As can be seen in Fig. 7, the pin 82 is disposed on actuating means 83 in a manner so that blocking member 80 is stopped in its toggle blocking position with actuating means 83 tilted to its counterclockwise extreme as determined by the depression 84 and the rod 29. In this position of the blocking member S0, a free end 86 of the blocking member extends into the path of movement of the toggle knee 37. The toggle knee 37 is moved from its initial position shown in Fig. 7 to its intermediate position (not shown) in engagement with the free end 86 of blocking member 80 by the action of lug 79 as the operating member 57 is moved clockwise about rod 29. The lug 79 is so disposed that it disengages knee 37 and imparts no further motion thereto while the operating member 57 continues moving clockwise after the toggle knee 37 has reached its intermediate position.

`From the foregoing detailed description of the structure of the second embodiment of my improved circuit breaker operating mechanism, its mode of operation may now be readily followed. In all respects except circuit breaker closing, the operation of the mechanism is essentially the same as that described above in connection with the rst embodiment of the invention. p

To close the breaker after it has been reset, the handle mechanism 58 is moved to raise crankpin 63 thereby pivoting the operating member 57 clockwise about rod 29. The operating member 57 while moving clockwise from its iirst to its second position carries pin 55 along the arc 66 illustrated in Fig. 7. When the operating member 57 has moved a relatively' short distance to a position such as that shown by way of example in Fig. 7, the operating member lug 79 engages the toggle knee 37. Further closewise movement of the operating member will result in lug 79 carrying toggle knee 37 upward, whereby switch closing movement of the toggle 30 and the interconnected linkages and members is initiated. Shortly thereafter, the operating member pin 55 passes through the extended centerline of

toggle links

34, 35, and switch closing force is exerted on the toggle knee 37 by the overcenter tension springs 52, 53. The moment of the spring force with respect to the pin 39 to which the toggle end 38 is pivotally attached is now in a direction tending to rotate toggle links 34, counterclockwise `on pin 39 and thereby tending to close the circuit breaker switch member 16, as has been explained hereinbefore.

As the operating member 57 continues in its clockwise course, the lug 79 moves toggle knee 37 into engagement with the free end 86 of the blocking member 80, whereby the toggle 30 is stopped in its intermediate position. The toggle is stopped in this intermediate position to prevent closing of the circuit breaker switch member 16 before the overcenter tension springs 52, 53 have been fully extended or charged, thereby ensuring that no closing action can take place at inconsistent points during the closing operation while less than full spring force is available. It should be noted here that the initial movement of the toggle and interconnected linkages is accomplished at a point during the closing operation where the force required to charge the overcenter springs 52, 53 is still relatively small.

As the operating member 57 approaches its second position and the overcenter springs have been stretched or charged to substantially their fullest extent, operating member pin 74 engages the surface 85 of the actuating means 83 thereby tilting the actuating means 83 clockwise on rod 43. As a result, pin 82 affixed to the actuating means forces the blocking member counter'- clockwise on rod 29, and the free end 86 of the blocking member is removed from the path of movement of the toggle knee 37 thereby releasing the toggle 3i) for snapaction switch closing movement in accordance with the force being exerted by the fully charged overcenter springs 52, 53. The closed circuit position of the second embodiment of the operating mechanism is shown in Fig. 8.

With the arrangement and operation described above, the duty of the overcenter tension springs is reduced and consequently weaker springs may be used to effect snapaction switch closing movement than would otherwise be possible. This is because the overcenter springs are obliged to move the toggle 30 only from its intermediate position. In the intermediate position of the toggle, the moment of the spring force has been increased. That is, the arm of the spring force with respect to the moment center at pin 39 is greater when the toggle is in its intermediate position than when the toggle is in its initial position shown in Fig. 7. Furthermore, less force is required to overcome the various motion-resisting forces when the toggle is in its intermediate position, because the toggle links 32, 33 are in a more favorable position. That is, the toggle links 32, 33 are disposed more nearly tangential to the rod 29 about which

members

24, 25 are pivoted, and consequently the force transmitted by links 32, 33 to pin 31 is more effective in moving

members

24, 25 and the other interconnected linkages and members of the force and motion amplifying means 21.

`During resetting of the operating mechanism, the toggle knee 37 rwill move along a path away from the blocking member until it is below the free end 86. As soon as the operating

members

56, 57 are started toward the reset positions, the blocking member 80 is able to pivot in a vclockwise direction on rod 29 in accordance with its bias until stopped by the pin 82 affixed to the actuating means 83.

`While I have shown and described a preferred form of my invention by way of illustration, many modifications will occur to those skilled in the art. I therefore contemplate by the claims which conclude this specilication to cover all such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. An operating mechanism for a circuit breaker having a movable switch member comprising: a toggle having one end connected to the switch member; latching means for releasably restraining the other end of said toggle in a latched position; an operating member movable between first and second positions at opposite ends `of its normal range of movement; an overcenter tension spring coupled at one end to said operating member and at its other end to said toggle and effective in response to movement of said operating member from said lirst to said second position to produce snap-action movement -of said toggle thereby producing circuit making movement of the switch member; and means movable with said operating member and engageable with said toggle to initiate movement of said toggle While said operating member is intermediate said rst and second positions and before said overcenter spring becomes eifective.

2. In a circuit interrupter: a switch member movable between open and closed circuit positions; a toggle having one end connected to said switch member; latching means for releasably restraining the other end of said toggle in a latched position; an operating member movable between iirst and second positions at opposite ends of its normal range yof movement; rigid means movable with said operating member and slidably engageable with said toggle to initiate movement of said toggle in response to movement of said operating member toward said second position; and an overcenter tension spring coupled at one end to said operating member and at its other end to said toggle and effective in response to movement of said `operating member after said rigid means has initiated movement `of s'aid toggle to produce snap-action switch closing movement of said toggle.

3. In a circuit breaker: a switch member movable between open circuit and closed circuit positions; a toggle having one end connected to said switch member; latching means for releasably restraining the other end of said toggle in a predetermined latched position; an operating member movable between first and second positions at opposite ends of its normal range of m-ovement; an overcenter tension spring coupled at one end to said operating member and at its other end to said toggle and effective in response to movement of said operating member from said first to said second position to produce snap-action switcli closing movement of said toggle, and stop means `engageable with said toggle to v stop said switch closing movement when said switch member reaches its closed circuit position, said stopV means being disposed to engage and stop said toggle in such a position that the forcel of said -overcenter spring will maintain said toggle in its stopped position upon returning said operating member to its rst position while said other end of said toggle is'in its predetermined latched position.

4. A circuit interrupter comprising: a' frame member; a movable switch member pivotally supported by said frame member; a toggle havingY one end connected to said switch member; a guide member connected to the other end of said toggle and mounted on-said frame for pivotal movement between iirst and second positions; a latch disposedreleasably to restrain said guide in its iirst position; an operating member pivotally mounted on said frame; a handle mechanism supported by said frame and positively coupled to said operating member for moving said loperating member between first and second positions; an overcenter spring interconnecting said operating member and said toggle and effective in response to movement of said operating member from its iirst to its second position to produce snap-action switch closing movementof said toggle; a movable catch disposed in cooperating relationship with said operating member for releasably restraining said'operating member in its secondv position; said overcenter spring being effective in response to guide releasing ioperation of said latch to drive said guide to its second position andl produce switch opening movement of said toggle; and means responsive to movement of said guide into its second position to engage and move said catch thereby releasing said operating member.

5. In a circuit interrupter: a switch member movable' between open and closed' circuit position; a toggle having one end connected to said switch member; latching means for releasably restraining the other end of said toggle in a latched position; an operating member movable between first and second positions at opposite ends of its normal range of movement; rigid means movable with said operating member and slidably engageable with said toggle to initiate switch closing movement of said toggle in response to the movement of said operating member toward said second position; an overcenter tension spring coupled at one end to said operating member and at its other end to said toggle to exert a switch closing force on said toggle as the operating member moves toward said second position; a'movable blocking member disposed in the path of movement of said toggle to stop switch closing movement thereof before said switch member reaches its closed circuit position;-and actuating means movable with said operating member and disposed to actuate said blocking member as said operatingv member approaches said second position thereby releasing said toggle for snap-action switch closing movement in accordance with the force exerted by said overcenter spring.

References Cited in the iile of this patent UNITED STATES PATENTS 1,753,975 Welch Apr. 8, 1930 2,188,949 Jackson Feb. 6, 1940 2,692,926 Cole Oct. 26, 1954